JPH07163987A - Complete treatment of water - Google Patents

Abstract

PURPOSE:To remove not only the chromaticity of iron, etc., but also the org. chromiticity of humic acid, etc., at the time of completely treating the polluted water such as river water and industrial waste water by bringing the raw water into contact with the electrolytic manganese dioxide grain impregnated with palladium in the presence of an oxidizing agent. CONSTITUTION:When the polluted water such as river water and industrial waste water is completely treated, the raw water is brought into contact with an electrolytic manganese dioxide grain impregnated with palladium in the presence of an oxidizing agent. Alternatively, the raw water is subjected flocculation treatment and then brought into contact with the grain. For example, the concd. raw water is introduced into a flocculating and settling tank 1 along with a flocculant, agitated by an agitator 4, subjected to flocculation and settlement treatment. The flocculated and settled sludge is drawn off, an oxidizing agent is added to the supernatant water, and the water is transferred to a catalytic treating tank 2 by a pump 5 and brought into contact with an electrolytic manganese dioxide grain impregnated with palladium.

Description

Detailed Description of the Invention

[0001]

The present invention relates to river water, well water, sewage,
The present invention relates to an advanced treatment method for water that is naturally or artificially polluted such as factory wastewater.

[0002]

2. Description of the Related Art As an advanced treatment method of this kind of water, there is known a method in which manganese sand coated with manganese dioxide is used as a catalyst as shown in FIG. 7, and an oxidizing agent is added to raw water in advance and then contacted with the catalyst. Has been. Since this method is mainly a method of removing chromaticity components such as iron and manganese in water,
The presence of organic chromaticity components such as humic acid and fulvic acid in water that cannot be sufficiently removed has the drawback that most of the organic substances such as BOD and COD (or potassium permanganate consumption) are also removed. I couldn't.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and the first object thereof is to maintain the chromaticity removal performance of iron, manganese, etc. by the conventional method. At the same time, it is another object of the present invention to provide an advanced treatment method for water, which can remove organic chromaticity such as humic acid and fulvic acid. A second object is to provide an advanced water treatment method capable of removing organic substances such as BOD and COD which could not be removed by the conventional method.

[0004]

The first invention made to solve the above problems is characterized in that raw water is brought into contact with electrolytic manganese dioxide particles impregnated with palladium in the presence of an oxidizing agent. It is a thing. The second invention is
After the raw water is coagulated, it is brought into contact with electrolytic manganese dioxide particles impregnated with palladium in the presence of an oxidizing agent.

[0005]

According to the advanced method for treating water of the present invention, oxygen adsorption on the palladium portion of palladium-impregnated electrolytic manganese dioxide particles → decomposition of pollutants, and decomposition of pollutants on electrolytic manganese dioxide parts → coexisting oxidant, chlorine-based oxidizer By repeating regeneration of MnO ₂ with permanganate, not only chromaticity in raw water but also organic substances such as BOD and COD which could not be removed by the conventional method can be removed. Treated water can be obtained.

[0006]

The present invention will be described in more detail below with reference to the drawings. In FIG. 1, 1 is a coagulating sedimentation tank, 2 is a contact treatment tank, 3 is a treated water tank, and the contact treatment tank 2 is filled with electrolytic manganese dioxide particles impregnated with palladium. Further, 4 is a stirrer, 5 is a coagulation-treated water transfer pump,
6 is a backwash pump and 7 is a backwash blower.

The palladium-impregnated electrolytic manganese dioxide particles filled in the contact treatment tank 2 have a particle size of 2-1.
It is obtained by adding metallic palladium at a rate of 0.1 to 0.5 g / kg to powdery manganese dioxide having a spherical or cylindrical shape of about 0 mm and γ-type crystals, and sintering it with alumina as a binder.
These particles have relatively low filtration resistance because they are relatively coarse materials to be used for filtration, and have a specific surface area of about 50 m ² / g and almost no adsorption power, but they have nearly 50% voids in the particles. Pollutants easily penetrate into the particles.

When the concentration of pollutants in the raw water to be treated is high, that is, when COD is about 5 mg / L or more (KMnO ₄ consumption is about 20 mg / L or more), the process shown in FIG. When the concentration of the pollutant in the raw water is less than the above value, the coagulation-sedimentation treatment is omitted from the flow of FIG. 1 and only the contact treatment with the electrolytic manganese dioxide particles impregnated with palladium is performed. The flow of FIG. 1 applied in the case of high concentration will be described below.

First, high-concentration raw water having a COD of 5 mg / L or more enters the coagulation-sedimentation tank 1 together with the coagulant and undergoes coagulation-sedimentation treatment. The aggregating agent used here is preferably an inorganic aggregating agent exhibiting acidity such as PAC and ferric chloride, and particularly ferric chloride having a high effect of removing organic substances at a pH of about 5 is excellent. This is because when the pH at the time of coagulation is as low as about 5 to 6, it not only has an acidic coagulation effect, but also enhances the effect of removing organic substances such as COD in the subsequent contact treatment with palladium-impregnated electrolytic manganese dioxide particles. This is because. Therefore, it is preferable to adjust the pH of the raw water to 5 to 6 even with low-concentration water that does not undergo the coagulation-sedimentation treatment. However, if the pH is set to 4.5 or less, the effect of removing COD etc. in the contact treatment will increase, but
May fall below the minimum water quality standard of 8.6.

FIG. 2 is a graph showing the relationship between the coagulation pH and the COD removal rate, and it is shown that the COD removal rate is high when the pH is as low as about 5 to 6 as described above. See also FIG.
Shows the relationship between the inlet pH of the contact treatment tank 2 and the COD removal rate, and the relationship with the highly treated water pH.
If it is 4.5 or less, the pH of advanced treated water is 5.8 to 8.6 which is the water quality standard.
It has been shown that there is a possibility that it may come off.

The sludge that has been coagulated and settled in the coagulation sedimentation tank 1 is discharged outside the system as drawn-out sludge, and the supernatant water is added with an oxidizing agent as coagulation-treated water, and then in the contact treatment tank 2, palladium-impregnated electrolytic manganese dioxide is added. Contact treatment with particles is performed. The oxidizing agent used here is preferably a chlorine-based oxidizing agent such as sodium hypochlorite and permanganate, and these oxidizing agents may be used in combination with pure oxygen or air.

The chromaticity of the manganese dioxide particles impregnated with palladium in the contact treatment tank 2, the oxidation reaction of organic substances and the regeneration reaction of the particles are carried out as follows.

## STR00001 ## Oxidation reaction (palladium catalyst, electrolytic manganese dioxide) Palladium catalyst: Pd + O → Pd.O [oxygen adsorption] Pd.O + organic matter → Pd + decomposed product [oxidation] electrolytic manganese dioxide: MnO ₂ + NaClO → MnO + NaCl

A chlorine-based oxidizing agent or a permanganate is an essential requirement for the regeneration reaction of electrolytic manganese dioxide, but oxygen adsorption of palladium does not necessarily have to be active oxygen derived from these oxidizing agents, and therefore pure oxygen is necessary. Alternatively, air can be used together. It should be noted that hydrogen peroxide, which is one of the oxidizers, foams violently when it comes into contact with palladium-impregnated electrolytic manganese dioxide particles, and ozone oxidizes manganese dioxide to permanganic acid, resulting in severe loss of palladium-impregnated electrolytic manganese dioxide particles. Therefore, it is not preferable to use either of them.

Next, the required amount of the oxidant is 20% of the theoretical required oxidant amount based on the COD standard in the case of a chlorine-based oxidant or permanganate in consideration of the treatment performance of organic substances and the concentration of the residual oxidant. -50% (1 / 3.95 of the consumption amount of potassium permanganate is the COD value) is preferable. This relationship is shown in FIG. When pure oxygen or air is also used, the chlorine-based oxidizing agent or permanganate can be reduced in proportion to the concentration of dissolved oxygen to be added. Further, in the contact treatment with the palladium-impregnated electrolytic manganese dioxide particles, even if the addition ratio of the chlorine-based oxidant or permanganate is constant, aeration with pure oxygen or air in advance to increase the dissolved oxygen concentration will further improve the treatment performance. Can be improved. This is a feature not found in electrolytic manganese dioxide that is not impregnated with palladium, as shown in FIG.

The processing condition in this contact processing is LV =
300 m / day or less, SV = 1 to 6 / Hr is desirable, and when the layer of palladium-impregnated electrolytic manganese dioxide particles is clogged, air backwashing → simultaneous backwashing → water backwashing is performed as in normal filtration. is necessary.

As described above, removal of chromaticity, organic matter, etc.
Palladium part of palladium-impregnated electrolytic manganese dioxide particles
Oxygen adsorption in water → Decomposition of pollutants and electrolytic manganese dioxide
Decomposition of pollutants in the cancer part → Coexisting oxidizer, chlorine-based oxidizer,
MnO with permanganate₂Repeated playback to
Therefore, it progresses. However, if the treatment is continued, the particle layer becomes clogged.
Marriage occurs. In addition, chlorine-based oxidizer or excess
When the amount of ganate is insufficient, the electrolytic manganese dioxide part
MnO produced by decomposition of pollutants ₂Part of is played
Instead, it adheres to the surface of the particles and the processing performance gradually deteriorates.
It

The particle layer may be clogged by washing the particle layer in the same manner as in ordinary filtration, but in order to reduce the treatment performance, an activation operation is required following the washing of the particle layer. This operation is performed by immersing the palladium-impregnated electrolytic manganese dioxide particles in a solution of a chlorine-based oxidizing agent such as sodium hypochlorite or a permanganate for a certain period of time. The immersion time varies depending on the type of oxidizing agent, but when sodium hypochlorite with an effective chlorine of 0.5 to 2% is used as an oxidizing agent for utilization, 5 to 20 minutes are required. The reaction formula at the time of activation is the same as the regeneration reaction at the time of treatment, and MnO + NaClO
→ MnO ₂ + NaCl.

The activation interval depends on the water quality such as COD of the raw water and the balance of the amount of the oxidizing agent to be added, but usually once every two days is sufficient. In the palladium-impregnated electrolytic manganese dioxide particles, the activation interval can be extended by adding pure oxygen or dissolved oxygen derived from air in addition to the chlorine-based oxidizing agent or permanganate. This is a feature not found in electrolytic manganese dioxide particles. Figure 6 shows the relationship between the activation timing and the recovery of COD removal rate.
Shown in.

In this way, the coagulation-sedimentation treatment → contact treatment is carried out to obtain highly treated water. When the COD of raw water is about 5 mg / L or less (potassium permanganate consumption 20 mg / L or less), there is no problem with the contact treatment with palladium-impregnated electrolytic manganese dioxide particles even if the coagulation-sedimentation treatment is omitted. Even in this case, when the SS in the raw water is about several tens mg / L or more, it is preferable to perform the coagulation sedimentation treatment.

As described above, the contact treatment with the palladium-impregnated electrolytic manganese dioxide particles is superior in chromaticity and removability of organic matter to the raw water as compared with the conventional method of using manganese sand. Precipitation over a wide range of COD and other organic matter concentrations (acidic precipitation)
Stable treatment can be performed by using in combination. In addition, this method not only improves the treatment performance by adding dissolved oxygen by aeration with pure oxygen or air in addition to the chlorine-based oxidizing agent or permanganate, but also can extend the activation interval.

Next, the data processed by the method of the present invention and the conventional method are shown. Table 1 shows data obtained by treating well water which is low concentration raw water, and Table 2 shows data obtained by treating secondary treated water which is high concentration raw water.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

As is apparent from the data of the above-described examples, according to the present invention, the contact treatment is carried out with the electrolytic manganese dioxide particles impregnated with palladium, so that the chromaticity and the treatment performance which are poor in the conventional method are The COD, KMnO ₄ consumption, BOD, and other organic substances that could hardly be removed by the conventional method can be significantly improved. At the same time, by using the coagulation / precipitation (acid coagulation by an acidic inorganic coagulant) in the previous stage together, stable treatment performance can be exhibited for a wide range of raw water concentrations.

[Brief description of drawings]

FIG. 1 is a flow sheet of the present invention.

FIG. 2 is a graph showing the relationship between aggregation pH and COD removal rate.

[Figure 3] Contact treatment tank inlet pH, COD removal rate, and highly treated water
It is a graph which shows the relationship of pH.

FIG. 4 is a graph showing the relationship between the oxidant addition rate and the COD removal rate.

FIG. 5 is a graph showing the relationship between the concentration of added dissolved oxygen and the COD removal rate.

FIG. 6 is a graph showing the time change of the COD removal rate and the activation timing.

FIG. 7 is a flow sheet of a conventional method.

[Explanation of symbols]

1 coagulation sedimentation tank, 2 contact treatment tank, 3 treated water tank, 4
Stirrer, 5 flocculation water transfer pump, 6 backwash pump,
7 Backwash blower

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C02F 9/00 504 B

Claims (2)

[Claims] 1. A method for advanced treatment of water, characterized in that raw water is contacted with electrolytic manganese dioxide particles impregnated with palladium in the presence of an oxidizing agent. 2. A method for advanced treatment of water, which comprises subjecting raw water to coagulation treatment and then contacting with electrolytic manganese dioxide particles impregnated with palladium in the presence of an oxidizing agent.